COST Action IC1205 on Computational Social Choice: STSM Report

A major focus was on the problem of randomised assignment, a probabilistic version of the house allocation problem. Here we tried to obtain a strong impossibility result (an incompatibility of an efficiency axiom and a weak strategy-proofness axiom) using computer-aided techniques that have recently been successfully used to produce sophisticated (but human-readable) proofs in a variety of fields within social choice. Our work as applied to the assignment problem is ongoing; it seems particularly challenging. In our probabilistic setting, because the search space has a more complicated structure than in a deterministic setting, solver performance is significantly worse, and so sophisticated problem-reduction techniques need to be used. We’ve only had the time to try out a few of the possible avenues to a solution, but plan to continue to work on this, and are optimistic that progress is possible using these techniques.